Data Migration

IncrementalMigration by Martin Fowler suggests the iteration process for a Data Migration task as a very important part.
I agree with the idea as a person who had just carried through a major migration. i have to say that business involvement is one of the most important things in the streamlining of the data transfer from one system to another.
The important thing that we do need to keep in mind and that Martin has not raised is the end system availability. business users love to see content as part of the website it should be in. the content management system is just a tool/hussle for them. they want to see the final product working with the migrated content and thus one of the requirements of a successful Data migration is the readiness of the preview system (Staging system).
Another thing that you gain from having a working system is less system bugs that crumple data looks and creating the false assumption that the data is corrupted.
Iterating through the data imported as part of the validation of data migration will uproot all the visual defects you can get when the content is not 100% like the developers expectations.
I know for a fact that our business users were struggling, without the preview system, to grasp contents structure and looks. Bugs descriptions were mainly on items visability and looks then order of content or content integrity.
So is the iterative process of content migration the route or full lifecycle migration the route?
That is not very clear. My belief is that the answer is project dependent.
If the ability to split the application and the content migration into chunks of the final product and they are small enough to be iterative then you got yourself an iterative project. But what happens if the application development covers a larger development effort prior to Data Migration even been testable? Even if we do the development in iterative mode, we will need to span the iterations of the content development after a large chuck of the system development is done.
But the main issue in choosing the correct path I believe is the boss. What type of client you have will probably determine the way you can manage your project and choose the development method.